Alesis QS7, Reference Manual

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Chapter 6: Editing Programs
LFO (L
OW
F
REQUENCY
O
SCILLATOR
)
The pitch, filter, and amp modules each have a dedicated LFO module for
modulation. The term LFO stands for low frequency oscillator, and comes from how
modulation was created in the early synth days (an oscillator set to a low frequency
could modulate some aspect of the sound; routing the LFO to the pitch, for example,
would create vibrato). The LFO creates a cyclic (periodic) modulation; this amount
can be constant and/or varied with a variety of modulation sources (mod wheel is one
of the most popular). Each LFO has a waveform shape and speed, along with other
controls.
E
NVELOPES
Envelope generators provide a modulation signal that varies over time, from the time
you strike the key until after you let go. There are three independent envelope
generators (for pitch, filter, and amp) in each Program Sound. An envelope generator
has different effects on different modules. Example: The Amp Envelope creates level
changes. Amplitude that decays over time creates percussive effects (plucked
strings, drums, etc.). Amplitude that increases over time gives the effect of brass,
woodwind, and some bowed instruments.
Each envelope generator has the standard attack, decay, sustain, and release
parameters found on most synthesizers, along with delay, sustain decay, and
different triggering options.
A
BOUT
S
IGNAL
P
ROCESSING
The QS features a signal processing section based on the Alesis QuadraVerb 2. It is
a complete digital signal processing unit with four input buses, simultaneous multiple
effects, and flexible signal routing.
Effects parameters are edited separately from either the Program or the Mix, using
Effects Edit Mode (more in Chapter 6). In Program Edit Mode, each of the four
sounds in the Program has its own Effect Level control and can be assigned to any
one of the four effect buses. Effects settings, Effect Level and Bus information are
saved with the Program when you store it back into memory.
52 QS7/QS8 Reference Manual